1. Field of Invention
The present invention relates to video processing, and more particularly to the generation of time-dependent control signals for video signals.
2. Background
Television systems have become increasingly complex as consumers continue to demand greater functionality and performance from television sets. Furthermore, the geographic diversity and business interests of manufacturers and service providers within the television and recording industries has lead to a plethora of analog and digital video formats. For example, analog video signal formats include National TV System Committee (NTSC), Phase Alternation Line Rate (PAL), and Sequential Couleur Avec Memoire (SECAM) television signals. Example digital video signal formats include ITU-R-656 and Digital Video Interface (DVI). Moreover, video processing devices, such as a televisions or cable set-top boxes, must be able to insert control signals within video signals as they are being processed for display. Such control signals are needed to support outputting video signals in different formats and to implement a variety of value added features including, for example, copy protection features, such as those contained within MACROVISION copy protection process standards. MACROVISION is a trademark of Macrovision Corporation.
MACROVISION copy protection technologies are designed to allow content owners to protect their videocassettes, digital Pay-Per-View (PPV) programs and digital video discs (DVD) from unauthorized recording on VCRs. In the context of PPV, MACROVISION copy protection allows consumers to view, but not record, programs that are distributed via digital set-top box decoders. To apply copy protection to a specific program, the direct broadcast satellite (DBS) operator or cable system operator transmits a software command from the uplink center or headend to its set-top decoders. An integrated circuit inside the decoder receives the command and adds the copy protection waveform to the video destined for the TV. The copy-protected signal is transparent on original program viewing, but causes copies made on the majority of VCRs to degrade to the extent that they no longer have entertainment value. MACROVISION's PPV copy protection technology degrades unauthorized copies on approximately 95 percent of the TV and VCR combinations in the market today. Virtually all digital set-tops in North America have copy protection capability, as do the majority of digital set-top boxes in international markets.
The MACROVISION copy protection process requires that integrated circuitry within a video processing device dynamically adjust to copy protection information transmitted with a video stream. In addition, the MACROVISION copy protection process is an evolving one in which the formats used periodically change. For example, the current MACROVISION copy protection process has been revised and updated several times, and is currently on Revision 7.1.S1. Implementation of the MACROVISION copy protection process has been previously implemented in hardware because of the need to quickly process MACROVISION input signals and generate control signals to adjust an output video signal. As a result, when revisions to the standard are made, updating deployed video processing devices that have used hardware to implement the MACROVISION standard is difficult.
What is needed are systems and methods for generation of time-dependent control signals that can efficiently provide control for video signals, implement the MACROVISION copy protection process, and provide other value added features.